1. doc.: IEEE 802.15-<doc#>
<month year>
doc.: IEEE <doc#>
Project: IEEE P Working Group for Wireless Personal Area Networks (WPANs)
Submission Title: Layer 2 Routing Final Proposal to Call for Contributions
Date Submitted: 13 July, 2014
Source: Seong-Soon Joo, In-Hwan Lee, Hyo-Chan Bang
Company: ETRI
Address: 161 Gajeong-dong, Yuseong-gu, Daejeon, KOREA
Voice: , FAX: ,
Re:
Abstract: As a final contribution proposal for the IEEE TG10 standards, the layer 2 routing specification is proposed.
Purpose: Response to the IEEE TG10 call for contribution
Notice: This document has been prepared to assist the IEEE P It is offered as a basis for discussion and is not binding on the contributing individual(s) or organization(s). The material in this document is subject to change in form and content after further study. The contributor(s) reserve(s) the right to add, amend or withdraw material contained herein.
Release: The contributor acknowledges and accepts that this contribution becomes the property of IEEE and may be made publicly available by P
<author>, <company>

2. Layer 2 Routing Final Proposal to Call for Contributions
<month year>
doc.: IEEE <doc#>
Layer 2 Routing Final Proposal to Call for Contributions
Seong-Soon Joo*,
In-Hwan Lee, Hyo-Chan Bang
ETRI
<author>, <company>

3. L2R Requirements (I) Mesh Topology Discovery Mesh Routing Protocol
external stimulus
changes in the presence of devices
changes in connectivity between devices
changes in the quality of the links
relearn the network topology
including the status and quality of links
Mesh Routing Protocol
protocol for dynamic auto-configuration of MAC-layer data delivery paths between devices
support proactive or reactive route discovery
support the use of sleeping end and sleeping routing devices
the route discovery or route maintenance process optimize the path of a route based on a metric or combination of metrics
routing metrics
radio ware: utilized include data rate, packet size, signal strength, link quality.
device aware: Energy constraints, Memory constraints
network aware
bridge aware
Extensible Mesh Routing Architecture
alternative path-selection metrics and/or routing algorithms
multiple path-selection metrics or routings algorithms
extensible to cope with the introduction of other metrics in the future
application or other higher layer to determine the path selection metrics or routing algorithms in network formation process

4. L2R Requirements (II) Requirements from Network Layer
Data Delivery in Mesh
unicast/broadcast/multicast
change operating frequencies
QoS
network acknowledgment of a multi-hop transmission
security
Entry and Exit points
select the most appropriate entry/exit point for their communications with entities outside the network
If unable to communicate with an entity outside the network, it shall be possible to find an alternative entry/exit point
use different entry/exit points to communicate with different external entities
Requirements from Network Layer
provide transparent link to network layer
support multiple grades of link
low latency of converging from

5. Link Network transparent link to network layer
routed link-path from a source to a destination device
constituted of links and virtual links
virtual links: established between two devices multi-hop apart
multi-hop link connection through the routers which perform frame relaying instead of routed forwarding
performed in two stages: link connection and link network routing
PAN coordinator
L2R router 2
device 6
router 5
router 4
router 1
device 4
device 1
device 2
device 8
router 6
device 7
L2R router 3
device 5
device 3

6. Link Network Reference Architecture
layered architecture
application/IP network
L2R network
MAC/PHY
Two sublayers for L2R network
MAC Link Control sublayer
reserve a resource for a link and virtual link
establish & maintain link and virtual link
MAC Link Network sublayer
maintain link-path routing information
manage link network
sublayer peer protocol
encapsulated in information element
L2R IE : header IE
L2R payload IE : payload IE
IEEE MAC
MAC Link Network (MLN)
Network
Application
MAC Link Control (MLC)
MLC-SAP
MLN-SAP
MCPS-SAP
MLME-SAP
IEEE PHY
L2RN

7. L2R Link Network Features
start a PAN
PAN coordinator scans, selects a PAN ID
start to transmit beacon
when receiving association request, assign a short address
setup a default link
device scans, selects coordinator based on distance to PAN coord, radio metric (RSSI)
connect on a default link, CAP, or access a media with CSMA-CA
join a PAN
send association request as a cluster root or not
get response from PAN coordinator with cluster matrix
initialize route table
maintain layer 2 routing
maintain cluster matrix as PAN coordinator, cluster root router, router
maintain route table
setup virtual links
setup a shared link or a dedicated link on two ends multi-hops apart
maintain link and link-path
maintain link table
maintain link-path table

8. L2R Link and Virtual Link
establishing a link or virtual link
default link
scan parent/peer
associate request command on CAP slot
receive associate response command on CAP slot, then default link is established
in non-beacon network, default link is established
shared/dedicated link or virtual
receive link establish request from higher layer
find link or virtual link, associate to the destination device with reserving the link resource
receive associate response command from the destination device, then link or virtual link is established
maintain a link or virtual link
primitives for link
MLC-LINK-SETUP.request/indication/response/confirm
link type (shared/dedicated,uni/bi), destination address, number of slots
MLC-LINK-RELEASE.request/indication/response/confirm
source address, destination address, link ID
MLC-MANAGEMENT.request/confirm
management type (HELLO/RESET), link ID

9. Setup Virtual Link over DSME MAC
as an example of dedicated virtual link
a virtual link over DSME MAC
a series of links that connects two devices by switching the time slots
my beacon
child 1
child 2
tier 1
coord
inner CAP link
inner inward shared link
inner inward dedicated link
my beacon
child 1
inner outward shared link
parent
neighbor
tier 2
router
outer CAP link
outer inward shared link
inner inward dedicated link
grand parent
parent
my beacon
outer outward shared link
outer outward dedicated link
neighbor
tier 3
router

10. Gateway router MLNE MLCE MAC sublayer Router 1 Higher layer
MLC-LINK-SETUP.request
(dedicated link)
data (L2R IE)
(link setup request command)
MCPS-DATA.confirm
MCPS-DATA.indication
MLME-DSME-GTS.request
DSME-GTS request command
MLME-DSME-GTS.indication
MLME-DSME-GTS.response
DSME-GTS reply command
MLME-DSME-GTS.confirm
MCPS-DATA.request
MLC-LINK-SETUP.indication
MLC-LINK-SETUP.confirm
(link setup response command)
MCPS-DATA.indicaiton
MLC-LINK-SETUP.response
additional sequence for bi-directional link setup

11. L2R Frames L2R frames define MAC header Information Element : L2R IE
define new MAC header IE and payload IE for L2R frames
use payload of MAC Data frame for L2R frames
define MAC header Information Element : L2R IE
L2R source/destination address
L2R link setup/release/hello command conveying as a link management subframe
define MAC payload Information Element : L2R Payload IE
L2R cluster formation/join/leave command
L2R route update command
L2R end-to-end flow control command
L2R IE
L2R Payload IE
Payload
L2R Subframe Control
Link Network Addressing fields
Link Management subframe
Link Network Management subframe
Frame Payload

12. Link Management Command Frames
L2R IE
L2R Payload IE
Payload
L2R Subframe Control
Link Network Addressing fields
Link Management subframe
Frame Payload
Bits: 0-1
Bits: 2-4 5 6 7 8 9 10
11-15
Protocol Version
Frame Operation Type
Destination Address Flag
Source Address Flag
Destination Address Mode
Source Address Mode
Link Flag
Link Network Flag
Reserved
Bits: 0-2
Bits: 3-7
Octets: 1
Octets: Variable
Link Management Command Type
Sequence Number
Length of Link Management Command
Link Management Command Payload
Link Management Command Type value
Command Type name
000
SETUP_REQ
001
REL_REQ
010
HELLO_REQ
011
Reserved
100
SETUP_RESP
101
REL_RESP
110
HELLO_RESP

13. Tiered Clusters in Single PAN
PAN coordinator centered tiered cluster
devices are randomly deployed around PAN coordinator
the distance to the PAN coordinator and distance to the neighbors increase when the device moving out from the PAN coordinator
group of device can be clustered according to the depth of tiers from PAN coordinator
PD 1a
tier 1
tier 2
PD 0
tier 3
PD 1b
PD 1c
PD 1b2a

14. Tiered Cluster-Tree Topology
addressing tiered cluster-tree
MAC short address = cluster identifier + device locator
cluster specified
maximum depth of the cluster (L)
maximum number of devices connected to a router (D)
maximum number of routers among devices connected to a router (R)
device locator (ZigBee Cskip address)
device identifier of a parent router (sequential order of a router at cluster depth h - 1)*size of address block at cluster depth h
size of address block
If R = 1, B(h) = 1+ D*(L- h-1)
If R ≠ 1, B(h) = (1+D-R-D*RL-h-1)/(1-R).
Root Cluster Tree 0
(L0, R0, D0)
Cluster Tree 1
(L1, R1, D1)
Cluster Tree 3
(L3, R3, D3)
Cluster Tree 2
(L2, R2, D2)
Cluster Tree 4
(L4, R4, D4)
Gateway router
(cluster ID = 0, locator ID = 0)
Cluster1 root
(cluster ID = 0, locator ID = i)
(cluster ID = 1, locator ID = 0)
Cluster2 root
(cluster ID = 0, locator ID = j)
(cluster ID = 2, locator ID = 0)
Cluster3 root
(cluster ID = 0, locator ID = k)
(cluster ID = 3, locator ID = 0)
Cluster4 root

15. Links of Tiered Cluster Tree
different size of cluster: (L,D,R) and B(h) = (1+D-R-D*RL-h-1)/(1-R)
if runs out of address block or route cost is over threshold, one of leaf device can create a child cluster as a cluster root
links
tree link based on the Cskip addressing
intra-cluster mesh link
inter-cluster mesh link
Root Cluster Tree 0
(L0, R0, D0)
Cluster Tree 1
(L1, R1, D1)
Cluster Tree 3
(L3, R3, D3)
Cluster Tree 2
(L2, R2, D2)
Cluster Tree 4
(L4, R4, D4)
Gateway router
Cluster1 root
Cluster2 root
Cluster3 root
Cluster4 root
inter-cluster
mesh link
intra-cluster

16. Tiered Cluster-Tree (TCT) Routing (I)
TCT routes
composed of link, virtual link in view of link control sublayer
composed of tree link, intra-cluster mesh, inter-cluster mesh in view of link network sublayer
routing information
link table
cluster connectivity matrix, Cskip addressing
inter-cluster mesh table
Root Cluster Tree 0
Cluster Tree 1
Cluster Tree 3
Cluster Tree 2
Cluster Tree 4
Gateway router
Cluster1 root
Cluster2 root
Cluster3 root
Cluster4 root
inter-cluster
mesh link
intra-cluster

17. Tiered Cluster-Tree (TCT) Routing (II)
with MAC address, find a cluster which a destination device is located at
check within same cluster
select inward or outward link based on address
not in same cluster
search possible paths to the destined cluster from cluster matrix, calculate route cost
select cluster tree link or inter cluster mesh link
check the default route, which obtains from cluster connectivity matrix, and route cost
check available virtual links for this route
search inter-cluster mesh link to reduce the route cost
search intra-cluster mesh link to reduce the route cost from the route table
select a link to transmit a frame to next hop
Root Cluster Tree 0
Cluster Tree 1
Cluster Tree 3
Cluster Tree 2
Cluster Tree 4
Gateway router
Cluster1 root
Cluster2 root
Cluster3 root
Cluster4 root
inter-cluster
mesh link
intra-cluster

18. TCT Routing Information Base (I)
PAN coordinator
PHY/MAC attribute
extended address, capability, PHY MIB, MAC MIB
PAN information
PAN ID, Beacon Interval, start time
PAN coordinator link table
PAN coordinator route table
cluster matrix, address allocation map
Temp routing information base
route update period, neighbor device table, neighbor link table
cluster root router
cluster root router link table
Root cluster route table
cluster matrix, cluster route table
router
PHY/MAC attribute
PAN information
router link table
router route table
cluster matrix, cluster route table
Temp routing information base
device
device link table
device route table
cluster route table

19. TCT Routing Information Base (II)
neighbor device table
device address
16 bit address (cluster ID + router ID)
64 bit address
link list
link
link ID
link type (CAP/CFP, default/shared/dedicated)
slot ID
link quality (RSSI, interference level)
queue load (frame count, loss count)

20. TCT Routing Information Base (III)
cluster matrix table
cluster root router address
16 bit address (cluster ID + router ID)
64 bit address
reflector address
address assigned in the parent cluster or
address of opposite end neighbor router on mesh link
distance to PAN coordinator
cluster configuration
depth/number of router/number of device
child cluster list
router address
16 bit address

21. TCT Routing Information Base (IV)
route table
destination device address
16 bit address (cluster ID + router ID)
route list
route
link ID
route cost (distance, link quality, router load)

22. TCT Routing Metrics routing metrics route cost calculation
link metrics
link type : weights among default, shared, dedicated link
link quality : signal strength, interference level
load balance : number of frame on a link, number of loss frame on a link
route metrics
distance : number of hops to destination
link cost
route cost calculation
l(link type) + n(link quality) + m(load balance) : apply normalized function
virtual link cost
sum of link cost on the virtual link (upward, downward)
route cost
number of hops to destination
sum of hop by hop link cost : link-path cost

23. Start L2R Link Network start router address assignment
if root router
association, cluster formation, then start
if router
association, then start
address assignment
root router  PAN coordinator
cluster formation
router  cluster root router
assign from reserved address block
primitives for starting L2R Link Network
MLN-START-NETWORK.request/confrim
PAN ID, scan channel, BO, SO, max depth, max router, max device
MLN-START-ROUTER.request/confirm
PAN ID, scan channel, max depth, max router, max device
MLN-START-DEVICE.request/confirm
PAN ID, scan channel

24. Gateway router MLNE MLCE MAC sublayer Router 1 Higher layer
MLN-START-ROUTER.request
MCPS-DATA.request
association request command
(L2R IE)
MLME-RESET.request
MLME-SCAN.request
MLME-SCAN.confirm
Higher layer
MLME-ASSOCIATION.request
(Allocate Address)
MLME-ASSOCIATION.indication
MLME-ASSOCIATION.response
association response command
MLME-ASSOCIATION.confirm
MLN-RESET
MLC-DATA-CLINK.request
(cluster formation request)
data (L2R IE)
(cluster formation request command)
MCPS-DATA.indication
MCPS-DATA.confirm
assign
cluster ID
(cluster formation response)
(cluster formation response command)
sequence of cluster formation
MLC-DATA-CLINK.indication
MLC-DATA-CLINK.confirm
establish default shared link
LN-START-ROUTER.confirm
MLME-START.request
MLME-START.confirm
load full cluster table

25. TCT Route Maintenance (I)
maintain virtual link and router
maintain virtual link
send hello periodically from source device to destination device
check link status
maintain cluster root router
PAN coordinator send hello periodically to cluster root router
check status of cluster root router
loss beacon for some amount of time
update routing information
update cluster matrix
cluster matrix for whole network, when joining link network
partial information above/behind a certain cluster root router
update route table of a cluster
whole route table, when joining link network
partial information above/behind a certain router
route information to specific destination

26. TCT Route Maintenance (II)
periodical update
cluster table
gateway  root router, root router  router
route table
router  root router
event driven update
start a PAN, join as a cluster root router, leave as a cluster root router
update cluster matrix and broadcast the changed part to cluster root router
join or leave as a router
update route table and broadcast the changed part to routers in the cluster
setup or release a mesh link
detect by periodically searching or upon router’s update request
if mesh link is inter cluster mesh link, change cluster matrix and broadcast
if mesh link is intra cluster mesh link, change route table and broadcast
loose sync, notified orphan from PHY/MAC
find an inward router and join again
if needed, to become a cluster root router requests to assign a cluster ID to PAN coordinator

27. TCT Route Maintenance (III)
Root Cluster Tree 0
Cluster Tree 1
Cluster Tree 3
Cluster Tree 2
Cluster Tree 4
Gateway router
Cluster1 root
Cluster2 root
Cluster3 root
Cluster4 root
inter-cluster
mesh link
intra-cluster

28. Gateway router MLNE MLCE MAC sublayer Router 1 Higher layer data
MLN-DATA.request (no route)
MCPS-DATA.request
MLC-DATA-CLINK.request (route update request)
Higher layer
data (L2R IE)
MCPS-DATA.indicaiton
MLC--DATA-CLINK.indication
MCPS-DATA.confirm
response or
forward
MLC--DATA-CLINK.request (route update response or request)
data (route update response command)
MCPS-DATA.indication
MLC-DATA-CLINK.indication (no route)
find route
MLN-DATA.confirm
data
data (route update request command)
(route update response)
MLC-DATA-SLINK.request
(data)
data (MLN data)
update route
MLC-DATA-SLINK.confirm
(route update request)
(route update request command)
MLC-DATA-SLINK.indication (route update request)
MLC-DATA-SLINK.request (route update request)
MLC-DATA-CLINK.confirm
DLC-DATA-CLINK.confirm
sequence of route update

29. Link Network Management Command Frames
L2R IE
L2R Payload IE
Payload
L2R Subframe Control
Link Network Addressing fields
Link Network Management subframe
Frame Payload
Bits: 0-1
Bits: 2-4 5 6 7 8 9 10
11-15
Protocol Version
Frame Operation Type
Destination Address Flag
Source Address Flag
Destination Address Mode
Source Address Mode
Link Flag
Link Network Flag
Reserved
Bits: 0-2
Bits: 3-7
Octets: 1
Octets: Variable
Link Network Management Command Type
Sequence Number
Length of Link Network Management Command
Link Network Management Command Payload
Link Network Management Command Type value
Command Type name
000
CLUSTER_REQ
001
UPDATE_REQ
010
LEAVE_REQ
011
FLOW_REQ
100
CLUSTER_RESP
101
UPDATE_RESP
110
LEAVE_RESP
111
FLOW_RESP

30. Data Service of L2R Link Network
frame forwarding
link type selection
primitive CLK/SLK/DLK & frame operation type
in/out decision
cluster connectivity matrix from cluster table
link selection (only for CLK/SLK data)
shortest cluster-tree route vs. mesh route
cluster table vs. route table

31. Summary virtual link link path load balanced link path maintaining
unbalanced cluster-tree based address assignment
tiered cluster-tree routing
directional multiple grades mesh connection
beacon-enabled multi-hop link network formation
MAC primitives & command frames